An image grab taken from a video released by the Islamic State (IS) and identified by private terrorism monitor SITE Intelligence Group on September 2, 2014, purportedly shows 31-year-old US freelance writer Steven Sotloff (AFP Photo)

A spokesman for the family of murdered journalist Steven Sotloff claimed Monday night that Sotloff was sold to the terrorist group the Islamic State in Iraq and Syria (ISIS) by Syria’s “so-called moderate rebels.”

Sotloff family spokesman Barak Barfi, a foreign policy research fellow at the New American Foundation, made the startling claim in an interview with CNN’s Anderson Cooper.

“We believe that these so-called moderate rebels that people want our administration to support, one of them sold him probably for something between $25,000 and $50,000 to ISIS and that was the reason he was captured,” Barfi said.

Asked how he knows this, Barfi referred to sources he and the Sotloff family have “on the ground.”

Made in the USA: Report Shows ISIS Using US Arms from ‘Syria Rebels’

From the moment the US began sending lethal arms to Syrian rebel factions, there were a chorus of people expressing fears that those arms would end up in the “wrong hands,” and US officials insisted they were going to carefully vet everyone who got those weapons.

You know who got a lot of those weapons? ISIS. Just as everyone predicted would happen, once the arms were smuggled into Syria, they quickly ended up spread out among rebel factions, both pro-US and not, and a new report shows massive amounts of ISIS armament was actually stamped “Property of US Govt.”

Some of those small arms were surely looted from Iraqi bases during the offensive in Mosul, which is also where ISIS got most of its arsenal of US-made military vehicles. That’s not the whole story, however.

The ISIS weapons, cataloged after being captured by Kurdish forces, also included US-made anti-tank missiles that appear to have been part of a delivery provided to the Free Syrian Army (FSA), one of those carefully vetted rebel factions.